A. Field of the Invention
The present invention relates in general to entertainment broadcast systems that transmit and receive a wide variety of video, audio, software and other types of data. More particularly, it relates to a multi-channel broadcast system that transmits a video/text/graphic-based program guide data stream that is used at viewer stations to generate a user interface that facilitates a user""s selection of various programs and services.
B. Description of Related Art
The use of electronic communications media to provide access to large amounts of video, audio, textual and data information is becoming more frequent. For example, the public switched telephone network (PSTN) is routinely used to transmit low speed digital data to and from personal computers. Cable television infrastructure is used to carry, via coaxial cable, analog or digital cable television signals, and may also be used to provide high speed Internet connections. In general, cable television infrastructures include many head end or transmission stations that receive programming from a variety of sources, then distribute the programming to local subscribers via a coaxial cable network. Large Direct-to-Home (DTH) satellite communications systems transmit directly to viewers over one hundred fifty audio and video channels, along with very high speed data. DTH systems typically include a transmission station that transmits audio, video and data to subscriber stations, via satellite.
One particularly advantageous DTH satellite system is the digital satellite television distribution system utilized by the DIRECTV(copyright) broadcast service. This system transports-digital data, digital video and digital audio to a viewer""s home via high-powered Ku-band satellites. The various program providers send programming material to transmission stations. If the programming is received in analog form, it is converted to digital. The transmission stations compress the digital video/audio programming (if needed), encrypt the video and/or audio, and format the information into data xe2x80x9cpacketsxe2x80x9d that are multiplexed with other data (e.g., electronic program guide data) into a plurality of bitstreams, which include identifying headers. Each packetized bitstream is modulated on a carrier and transmitted to a satellite, where it is relayed back to earth and received and decoded by the viewer""s receiver station. The receiver station includes a satellite antenna and an integrated receiver/decoder (IRD). The IRD may be connected to appropriate output devices, typically including a video display.
In general, DTH satellite(s) broadcast on several frequencies from multiple transponders at differing polarizations (e.g., left and right hand circular polarization), and each transponder bitstream includes the video and audio data packets (in a compressed format) for several different programs (or xe2x80x9cviewer channelsxe2x80x9d). For example, transponder ONE may broadcast the digital video and audio data packets for ESPN, TNT, AMC, AandE, EI, STARZ and USA, in a statistically multiplexed fashion. Satellites or other distribution systems which require separate input processing (e.g., satellites at two separated locations requiring different antennas) may also be used. Accordingly, in order to receive a desired viewer channel, the receiver station must know the transponder frequency and the polarization at which the desired signal information is being broadcast by the satellite, along with the identifying header information for those data packets on that transponder that relate to the desired program to permit its isolation from the multiplexed bitstream.
Each satellite transponder broadcasts a program guide data stream, which typically includes not only broadcast schedule data, but also the aforementioned information that the receiver station needs in order to tune to a particular channel. The program guide data stream is broadcast on all satellite transponders so that channel selection information is always available to the IRD regardless of the channel to which the IRD is tuned.
The data packets are distinguished from one another by their header information, which is referred to as the packet""s xe2x80x9cservice channel IDxe2x80x9d (SCID). For example, if a viewer instructs the IRD to display ESPN, the IRD, via the tuning information in the program guide data stream, determines the transponder frequency and polarization at which the ESPN programming is broadcast, along with the SCIDs of the data packets that are needed to generate and display the-video, audio, and data content of the ESPN program.
The scheduling data in the program guide data packets also provide channel and program-attribute information that is used by the IRD to construct and output as a viewable display (which may be a full or a partial screen) a text-based listing of programming channels, times, titles, descriptions, ratings, etc. In operation, a program guide display is typically presented as a grid having channels listed along the left, times across the top, and program titles shown within the grid squares. Users can scroll through the grid, either up and down (by channel) or to the left and right (by time). Channels can be selected by inputting the channel number directly using the number keys on a user""s remote control, or channels may be selected from the program guide display by highlighting and selecting a currently broadcast program that is listed in the grid. In either case, the IRD tunes to the chosen channel by accessing the channel""s transponder (frequency), polarization, and SCID information denoted by the program guide data stream.
An extension of known IRD equipment is a PC-based system that allows users to receive, directly into their PC""s, the same digital video, audio, and related information signals received in conventional DTH systems. The receiver station in this PC-based system includes a local satellite receiver dish similar to that of a conventional IRD system, but the IRD functions are implemented within the PC architecture through the use of one or more circuit boards that are inserted into the PC. The decoded outputs from these boards are displayed on the PC""s monitor, or may be output to a conventional video display (e.g., a television set) and/or other mass storage medium: such as magnetic tape, digital video disk (DVD), optical or magnetic disk, video recorder (VCR), etc. Because the receiver station includes a personal computer, a large number of additional data and software-related services can also be downloaded directly to the PC, thereby offering a variety of services, including broadcast programming, pay-per-view events, audio programming, data services, webcasting, software downloads and other data or software-related services.
While known program guides have advantages, there is still room for improvement, particularly when considering the large number of data, software, video, audio, pay-per-view and other programming services available through present and future DTH satellite broadcast services. For example, the viewable display generated from electronic program guide data tends to be presented primarily as text laid out in a grid. The processing power of currently available IRD""s, while appropriate for current DTH programming services, inherently limits how the program guide can be. displayed, how much information can be incorporated into the guide, and how quickly and efficiently a user can move through the guide. These program guides are therefore essentially limited to conveying program availability and tuning information, and do not have the organization and flexibility to effectively support other services such as software downloads, webpage links and downloads, data services, and other functions.
Accordingly, for broadcast systems having a large number of services that deliver a large amount of data to relatively sophisticated receiver stations (e.g., a PC), there is a need for a broadcast electronic program guide and an associated viewable display format and content that significantly enhances how the program guide can be displayed, how much information can be incorporated into the guide, and how quickly and efficiently the user can move through the guide.
The present invention provides a method and apparatus for efficiently and effectively transmitting, receiving, organizing and selecting transmitted data. The method and apparatus of the present invention is preferably embodied in a user interface and related data protocols and procedures. The user interface may be implemented in the context of a wireless distribution system for securely, reliably and inexpensively distributing video, audio, data service, software and other services to geographically remote receiver stations. The wireless distribution system is preferably a DTH digital satellite television distribution system, though other systems (e.g., terrestrial wire, cable, or wireless broadcast) may also be used in other embodiments. A typical DTH digital broadcast system includes a transmission station, a satellite relay, and a receiver station. At the transmission station, video and audio programming signals are digitized in known manners, multiplexed with other data signals (such as the data needed to construct a program guide display according to the present invention), compressed (if required), encoded, mated with error correction codes, modulated on carriers, and uplinked to a geosynchronous satellite. The satellite receives the uplinked signals and rebroadcasts them over a footprint that preferably covers a predetermined geographical area, for example, the continental United States. Receiver stations, which are typically located at the user""s home or business, receive the satellite signals. The receiver stations each include an antenna, which preferably is in the form of a satellite dish, along with an integrated receiver/decoder (IRD). The antenna feeds the received satellite signal to the IRD unit which recovers the originally transmitted digital video, audio, and data. Other receiver station equipment (e.g., cable decoder units) may be used with other distribution systems in other embodiments, as is well known in the art.
The present invention is particularly applicable to a receiver station having sufficient processing power to process and generate a program guide display and associated features that goes beyond conventional video/text/grid program guides. The processing power may be incorporated directly into the IRD, for example, by adding a more powerful microprocessor, more memory, and associated software to the conventional IRD circuitry. Alternatively, the receiver station IRD may be replaced with a PC having circuit cards that perform the IRD functions. A PC-based system significantly increases the receiver station""s processing power, along with the number of services (e.g., data services and software) the receiver station can receive and use. Accordingly, the features of the present invention are most advantageously utilized by a PC-based (or comparable) receiver station.
A PC-based receiver station suitable for use with the present invention includes an antenna, which preferably is in the form of a satellite dish, along with a PC which, like the above-described IRD, recovers the originally transmitted digital video, audio, and data. The digital broadcast data received from the satellite dish is coupled directly into a transport circuit board within the PC. The PC""s transport circuit board also performs initial circuit functions on the signal coupled in from the antenna, including tuning, demodulation, and forward error correction (FEC). The transport circuit board within the PC also performs similar functions to that of the IRD""s transport circuit, including channel de-multiplexing, decryption and access determination. The received digital broadcast data is sent from the transport circuit to video/audio decoder circuits, which may be on the same or separate circuit board. The video/audio decoder circuit board decompresses and/or decodes the received compressed broadcast signal.
In one embodiment of the present invention, the transmission station transmits to the receiver stations program selection data/information that is used at each receiver station to construct an electronic program guide and associated display format and content (i.e., a user interface) that, in contrast to known video-based and/or text/video/icon-based electronic program guides, significantly enhances how the program guide can be displayed, how much information can be incorporated into the guide, and how quickly and efficiently the user can move through the guide. The viewable display format, according to the present invention, incorporates moving picture video, still pictures, text, links to external data sources, graphics and other features that facilitate the selection of various programs and services.
The electronic program guide features of the present invention further provide a novel channel-selection process in the form of a graphical representation of a xe2x80x9ctuning bar.xe2x80x9d The tuning bar includes a movable slider that shows current tuning information (channel number and call sign) for the programming or service that is being shown in a main viewing area of the display. Moving the slider (typically using a mouse-controlled click and drag operation) changes the tuning which changes what is displayed in the main viewing area. Moving a cursor over any portion of the bar xe2x80x9cpops upxe2x80x9d the channel/call-sign associated with that portion of the bar. The received data that provides tuning information to the tuning bar is automatically scaled to accommodate the number of channels that are available at that station, so that the channels are evenly spread out along the bar (without gaps) regardless of the number of channels to which the user subscribes. Also, incremental xe2x80x9cupxe2x80x9d one channel and xe2x80x9cdownxe2x80x9d one channel buttons are preferably provided.
The electronic program guide features of the present invention incorporate still another novel channel-selection procedure wherein a replica of a conventional remote control unit is provided as part of the display. The remote control display has graphical push-buttons that correspond to those found on actual remote controls used for conventional stereos, video recorders, televisions, DTH, or cable television systems. In embodiments wherein the receiver station includes a personal computer (PC), this feature gives the user the option of a xe2x80x9csimulated remote controlxe2x80x9d interaction that the user may find more comfortable than using a mouse or keyboard alone. In an important embodiment, the button selections that make up the remote control display graphic change to fit the options available in the current screen, providing a context sensitive operation. Also, the receiver station may provide a remote control display having a shape and button layout that corresponds to a particular manufacturer""s physical remote control. If, for example, the user""s television and other peripherals are from RCA(copyright), the system may display a remote control graphic having a shape and button layout that corresponds to the actual remote control for the user""s RCA(copyright) TV, VCR and/or IRD.
The electronic program guide features of the present invention incorporate still another novel display presentation in connection with web-related services such as a xe2x80x9cBest-of-Webxe2x80x9d broadcast service, wherein website data is cached at the receiver station for convenient future access and/or links are provided for a real-time connection. When the user attempts to access this service, a list is generated and displayed showing the different websites and webpages that are available. In addition to the displayed list, the system maintains and stores a status list (or hash table) that may include an indication of the medium through which the page/site is available and, in the case of data subject to being cached, the status of the cache (i.e., whether or not the data is cached at the receiver station""s memory). Moving the cursor over one of the entries of the displayed table/list, prompts the system to automatically search the information in the status list and determine whether or not the page is available locally. For example, some webpages on the displayed list are cached in the receiver station""s memory, some are available through a future broadcast, while others can only be retrieved via direct access to the Internet. For data that is to be cached, the user interface/display, via supporting software, immediately checks the status list and determines whether that webpage is presently cached, and generates a pop up graphic (e.g., the universal xe2x80x9cnoxe2x80x9d symbol) that communicates to the user immediately whether or not that webpage is presently cached. This can be done in essentially real time because the receiver station maintains the status list of the cached webpages and searches that status list when the user moves the cursor over a webpage selection, without need to otherwise interrogate the system or the main system memory.
In accordance with another aspect of the present invention, broadcast (or xe2x80x9cwebcastxe2x80x9d) webpages may be archived on a user""s PC for later viewing. A webcast is a constant and repeating download of specially selected web content. The content is usually grouped by domain. Minimal scheduling is required for downloading webcast information. Multiple groups of content may be identified by the same identifier, thereby creating a one-to-many relationship among the items of interest.
As webpage information is received by the subscriber unit it is stored for later use. Preferably, the broadcast system uses an archiving scheme based on the ZIP format to group domain information. However, other alternative archiving formats may be used so long as both the sender and the receiver have a common set. If the archived files are compressed, the files are preferably extracted or decompressed using so-called xe2x80x9cextractorxe2x80x9d software, an example of which is sold under the tradename PKWare(trademark), which is a data compression library (DCL) compatible extractor. If, however, the files are not compressed, any ZIP extractor may be used to extract and view the files. Preferably, the filenames used in the webcast archive are the uniform resource identifier (URI).
Webcast archive files may have a dedicated filename extension convention. On any given data carousel, the contents of which are repeatedly broadcast, there must be exactly one main file for each webcast. This file contains a snapshot of the entire website. According to the present invention, update archive files are used to replace portions of the main file on the carousel. The subscriber unit stores all archive files in a subdirectory corresponding to the session ID of the webcast. When a main file is received that is newer than the current main file in that directory, all other files in that directory will be removed and any links in the proxy server""s cache map file for this webcast will be replaced with the URIs in the new main file.
The invention itself, together with further objects and attendant advantages, will best be understood by reference to the following detailed description, taken in conjunction with the accompanying drawings.